Electric signaling



June 7, 1932. L BGIN 1,862,106

ELECTRIC S IGNALING Filed July '7, 1,926 l 4 Sheets-Sheet l jnoemozLUCIEN BEGIN June 7, 1932, l.. BEGIN 1,862,106

ELECTRIC SIGNALING Filed July '7I 1926 4 Sheets-Sheet 2 COUPL//VG MEANSc LUCIEN BEGIN June 7, 19532.

L. BGIN ELECTRIC S IGNALING Filed July '7l 1926 4 Sheets-Sheefl 3 AMW!AMW/WM5 APPARATUS v mam/v6 MEA/v5 June 7, 1932.

L. BEGIN ELECTRIC SIGNALING Filed July 7, 192e 4 Sheets-Sheet 4 vwemtozLUCEN BEGI N @5% his @Hoff/mm3 MFWUZLLLM Patented June 7, 1932 UNITED:stairs-s .earner esi-uca LUCE-N BGIN; OEPARIS, FRANCE, ASSIGNOROFlONEv-HALF TD WILIIA'MvB.- WEAVERg 0F 'I BIRMNG-ILAT'L2-ALABAMK, AND,HAROLD.` IIHELM," OF NEV'YO'RK, NQ Y.

ELECTRIC SIGNALING.

Application filed July 7, 1926, Serial No. 120,917, and inFrance Ju1y1S, 1925.

This inventionrelates to electricsignalingv and particularly tomultiplex carrier wave telephony or telegraphy. l

One of' the Yprincipal object-s ofk the inven tion is the provision ofimproved means for,

morel effectively eliminating the difficulties encountered indifferentiating the different frequencies,' for example, thetransmitting andv receivingWaves of argivenl channel.

ii Other objects and'advantages of-the invenf forA differentiatingatransniittedwave from a received wave and affording absolutenoninterferenceof the'transmitted wave on the receiver.

Fig.' 2 is aschematic diagram of a system fordifferentiatingatransmitted wave from two received Wavesof'differentfrequency and affording absolute noni-interference of thetransmitted i wave on the receiver.

tgaj is a schematic-'diagram of ak system for Vaccomplishing thesanie'result's as Fig. l by the use of' diiferent'methods.

Fig. lis a schematic diagram ofa system for accomplishing-the sameresults as Fig. 2 lb v the use of'different methods.

Fig; 5 isa scliematic'diagram of'a system similar to Fig; 4 with theexception that ad# ditional means are provided 'fordiffereiitiatingthe-two received frequencies.

Fig. 6 is a schematic diagram of a system vsomewhat similartoFigureslnnd 3.

Figures 7`to l0 inclusive are schematic dia- ;rjranis ofvarioussystemsin which doubleV dif- 'c rr-irtiationV between the-sendingandreceiifuur channels are effected."

It is' known that it-is possible to effect carrier-Wave signalinginduplex, that is to say in amanner similar to that of an ordinarytelephone, by means; of'one and the saine carrier-wave frequencyproviding the trans- J initter output loe-made into the transmittingmediumdiiferentially'with respect to the receiving apparatus alsoassocla-teditherewith, andin sucha manner that the receiver 'will beconnected to equipotential points from the point of view of thetransmittedwaves whilst remaining in a condition to be operated'loyA thewaves emitted by the remote correspond; ent.

While this method has the advantage of" necessitatingv but a singlecarrier-waveV fre- F quency foreach duplex'fchannel, it comprises of thetransmitting power', is of difficult construction and of unstableoperation. For this reason, this system is notwidely' usedfanditV isgenerally preferred to sort out"the'trans# mitted andreceivedvvavesniainly byusing Waves ofdifferent frequencies.

This latter method is quite satisfactory' when thev power involved for'transmission does not eXceed'certain limits Withrespect'to that which isavailable for. operating the rev ceiver andprovidingitransmission takesplace on a carrier-Wavefrequency'which is suiiii ciently different fromthat of. thereceivedA` waves. Now, in theicase Where it is' desired tosimultaneously carry out several duplex" communications7 this necessaryspacing' of theV various signalingv frequencies involveskr seriousdifficulties in this that, conditions 'belA ing otherwise equal. theattenuation `of the various channels is widely different depending" ontheir frequencies.

Ori-the other lia-nd when duplex operation' is effected at very highfrequencies, t-lie power" put into play at the transmitter is, for simi'lar reasons of attenuation, necessarily atV a much higher level thanthat available'for the" f* operation of the local receiver land thediiii culties encountered in sorting outV the dif;r ferent waves areconsequently increased: The use of electrical resonancephenoinena or offiltering-circuits, which is usually re'-4 sorted to, does not enableabsolutetliferem tiation and there always exists ar cert-ain amount ofmutual interference betweenthei" various channels.

branchedacross equipotentialipoints with re'- spect to the currentflowing through the other elements and this result is arrived at withoutresorting to balancing arrangements the operation of which is subject tothe state of the transmitting medium. The invention moreover enablesdecreasing the intervals between the frequencies used for the variouschannels with the consequent advantage of obtaining more uniformattenuation.

Referringto Fig. 1, the transmitting apparatus is connected to thewinding 120 of transformer 121, one terminal being connected directly toone extremity of the winding and the other terminal being connected tothe other extremity of the winding through a rejector 122 and areactance coil 123, as shown. The rejector 122 comprises the usualreactance coil and condenser in shunt therewith, as shown.

One extremity of winding 124 of transformer 121 is connected to oneextremity of winding 125 thru resistance 132. The other extremityofwinding 124 is connected to the other extremity of winding 125 thru arejector 126 and reactance coil 127 connected in series therewith, asshown. The rejector 126 is of the usual type, comprising a reactancecoil and a condenser in shunt therewith. The receiving apparatus isconnected across equipotential points of the windings 124 and 125, asshown.

Winding 128 of transformer 129 is connected to the coupling apparatus,which is in turn connected to the transmitting medium, as shown. Thetransmitting medium may be the conductors of a power transmission systemor may be ordinary telephone or telegraph conductors or may be anantenna, etc.

Let f1 be the received signal frequency or frequency band and f2 thetransmitted frequency or frequency band, the comparative magnitudes ofthe frequencies being denoted by the subscripts. V

Rejectors 122 and 126 are arranged to offer a large impedance to rFheserejectors will therefore oder a small capacity reactance to f2. This isneutralized by the inductive reactance of coils 123 and 127. Therejectors offer substantially zero impedance to f2 and very smallresistance thereto. The resistance tol f2 offered by rejectors 126 isexactly balanced by resistance 132.

This system functions in the following manner. .The transmissionfrequency f2 is easily conveyed tothe transmission medium thrutransformers 121, 129 and the coupling apparatus, in view of the factthat rejectors 122 and 126 offer substantially zero impedance, thereto.Owing to the fact that the receiving` apparatus is connected acrossequipotential points of coils 124 and 125, as far as f2 is concerned,current of frequency f2 will not influence said apparatus.

Now'assume that receiving frequency f1 makes its appearance in coil 125.Rejector 126 precludes the passage of this frequency thru the lowerparts of coils 124 and 125. Ourrent of frequency f1 may now flow thruthe receiving apparatus as the points which were at equal potential forfrequency f2 are not at frequency f1. It is of course to be understoodthat both transmission and reception may go on separately orsimultaneously, the separate functioning being described for the sake ofsimplicity. Rejector 122 prevents the received frequency f1 frominfluencing the transmitting apparatus.

Referring to Fig. 2, in which like numerals indicate similar parts, thereceiving apparatus is arranged to receive frequencies f1 and f3; whilethe transmitting apparatus is arranged to transmit frequency f2.Frequency f2 is halfway between frequencies f1 and f3.

One terminal of the transmitting apparatus is connected to one extremityof coil 12() of transformer 121 through rejector 122. The other terminalof the transmitting apparatus is connected to the other extremity ofcoil 120 through rejector 130, as shown. Rejector 122, rejects y, whilerejectors 130 reject f3. The transmitting apparatus is therefore notinfluenced by received frequencies f1 and f3.

The rejectors 122 and 130 together are tuned to the transmittedfrequency f2.

One terminal of coil 124 is connected to one terminal of coil 125through two rejectors 126 and 131, the said rejectors being connected inseries with each other as shown.

Another terminal of coil 124 is connected to another terminal of coil125 through a resistance 132. The terminals of coil 128 are connected toapparatus similar to that described in connection with Fig. 1, as shown.

Rejector 126 rejects frequency f1 while rejector 131 rejects f3, the twotogether oifer- 4 'ing substantially Zero impedance to the transmittedfrequency f2. Resistance 132 equals and balances the resistance offeredto frequency f2 by rejectors 126 and 131.

This arrangement. functions in a manner similar to that described abovein connection with Fig. 1, the only difference beingl the a1'- rangementis capable of receiving two frequencies. Due to the fact that thereceiving apparatus is connected across equi-potential points as far asthe transmit-ted frequency is concerned, it is non-influenced thereby.

Referring to Fig. 3 in which like numerals indicate similar parts, oneterminal of the transmitting apparatus is connected to one terminal ofthe coupling apparatus thru rcsistance 133, as shown. The other terminalof the transmitting apparatus is connected to the other terminal of thecoupling apparatus thru a reactance device 134, as shown. Reactancedevice 134 comprises a rejector 135A and a condenser 136 connected inseries there r with, as shown.

The rejector 135 rejects` received. frequency 2;V but' permits the easypassage of trans mittedfrequency f1. The slight inductive rc-` u actaneeoffered to. f1 is neutralized bycondenserl 136. Thereactance :deviceWill offer al certa-inamountof resistance to the passageof.thetransmittedfrequency f1. This resistance is balancedby resistance133.

Aeresistance device v137 and a resistance 138 are connected in seriesWith each other immediately-across the terminals of thetransmittingapparatus, as shown. The reactance device 137 comprisesarejector 139 and an inductive reactance-140 connected in series 5* withea-ch-...ot-her, as. shown.Y

A reactancedevice 141' and-a resistance 142 are connectedin series Witheach other immediately acrossthe ,terminals of the coupling'apparatus,as shown. The reactance 0* device 141 comprises a rejector 143 and aninductive reactance-'144 connected in series therewith, as shown'.

The-rejectors139'and 143 reject the transmittedfrequency f1; but permitthe easy passage/of the received frequency f2. The capacity reactanceoffered to f2 by rejectors 139 and '143 is neutralized by inductivereactancecoils 140 and 144, r-espectively.

One terminal of the receiving .apparatus 39 is connected betweenresistance 138 and re-` actance device-137,` as shown. The otherterminal is; connected between resistance 142 and reactance'device 141-,as shown. The connections constituteequiepotential points for theTreceivingapparatus-With respect to the transmitted frequency f1 Ybutare not with respect to the received frequency In vie-W ofl thefact thatit is impossible to realizey pure reactances devoid of resist- "ance,the reactancey devices137 and 141 Will give rise -to aslightconductance:when functioning; as rejectorsandto a slight effective resistance whenfunctioning as short circuits. Resista-nces 1381and 142 are arranged toneutralize'the leakage of reactance devices 137 and, 141, respectively,at frequency f1. The resistances 138 and 142 may be connected in serieswith coils 140 and 1447 respectively, so that the small' currents .Whichtheya-bsorb at frequency f1 may also show the` same phase angle as thatabsorbed by the reactance devices: f

This: arrangement lfunctions in the following manner: Rejectors 139 and143 prevent sthe passage of the transmitted frequency f1 thru thereceivingfapparatus: While rejector 135' permits the passage of fl'tothe coupling apparatus. As the receiving apparatus is connected acrossequiepotential points With *respecttozfl', itis not influenced thereby.As the rejectorf135 preventsthe passage of f2, the-'receiving apparatusis no longer connectedacrossequi-,potential points with rer spectto'received: frequency f2 and is infine 6l"tensed thereby; Rejector 135prevents the transmit-ting apparatus from being, inilu+L enced by thereceived frequency f2. It isto be understood that transmission andreception may go on simultaneously.

Referring; to F ig. 4, in Which like numerals indicate similar parts,one terminal of the transmitting apparatus is connected to one terminalof the coupling` apparat-us thru oalancing resistance 145. as shown. Theother terminals are connected together thru rejectors 146 and 147, thesaid rejectors being connected in series as shown. Rejector is arrangedto reject received frequency f1; While rejector 147 is arranged toreject received frequency f3. The two rejector-s together are thereforeresonant to transmitted frequency f2, said frequency being intermediatebetween that of f1 and f3. Rejectors 146 and 147 naturally offer acertain amount of resistance to f2. This is balanced by resistance 145.

A react-ance device 147e and a large resistance 148 are connected inseries With each other immediately across the terminal of thetransmitting apparatus, as shown.

A reactance device 149 and a resistance 150 are connected in series4with each other immediately across the terminals of coupling apparatus,as shown.

leactance device 147@ comprises a rejector 151 and an inductivereactance 152 connected in series therewith, as shown. Reactance device149 comprises a rejector 153 and an inductire reactance 154 connected inseries therewith, as shown. Rejectors 151 and 153 prevent the passage off2; but permit the easy passage of f1 and f3. Coils 152 and 154 andresist-ances 148 and 150 perform similar functions as coils 140 and 144and resistances 138 and 142 in Figure 21.

The terminals of the receiving apparatus are connected acrossequi-potential points in far as the transmitted frequency f2 isconccrned; but are not so connected With respect to received frequenciesf1 and f8. As the functioning of this system is similar to that of Fig.21, the only difference being the possibility of reception of twofrequencies, a detail description of the same is thought to beunnecessary here.

Referring to Fig. 5, in which like numerals indicate similar parts, asystem is disclosed forseparating the received frequencies fl' and f3from each other. This system is substantially a combination of thelsystems disclosed in Figures 3 and 4. A detailed description ofthe sameis therefore thought to be unnecessary here.

Referring to F ig. 6, which combines in part the systems shown byFigures 1 and 3 and in `Which like numerals indicate similar parts, oneterminal of transmitting apparatus is lconnected to the mid-point ofwinding 155 ofV transformer 156, asshoivn.r The lother terminal isconnected to the extremities of winding as shown.

One extremity of winding 157 is connected to one extremity of winding158 thru resistance 126, as shown. The other extremity of winding 157 isconnected to the other extremity of winding 158 of transformer 159 thrurejectors 126 and inductive reactance coil 127, connected in seriestherewith, as shown. Rejector 126 rejects the received frequency f1; butpermits the easy passage of the transmitted frequency f2. Coil 127neutralizes the slight capacity reactance offered to f2 by rejector 126.Resistance 132 balances the resistance offered to f2 by rej ector 126and coil 127. f

A rejector device 134 is connected between the upper extremity ofwinding 157 and its mid-point. This device comprises a rejector 135 anda condenser 136 connected in series therewith, as shown. Bejector 135rejects f2 but permits the easy passage of f1. The slight inductivereactance offered to f1 is neutralized by condenser' 136. A resistance160 is connected across the lower extremity of coils 157 and itsmid-point as shown. The terminals of the coupling means are connected tothe mid-points of acoils 157 and 158, as shown. Coil 161 is connected tothe receiving apparatus, as shown.

This system functions in the following manner: Current of frequency f2passes upward in upper half of coil 157, thru resistances 132, downwardin upper half of coil 158 to one terminal of the coupling means andthence to the mid-point of coil 157 thereby completing a circuit.

Current of frequency f2 also passes downward in lower half of coil 157,thru rejector 126, reactance coil 127, thence upward thru lower half ofcoil 158 to one terminal of the coupling means and from the otherterminal of the coupling means to the mid- `icint of coil 157. It is tobe noted that currents are flowing in opposite directions in coil 158.This results in Zero currents in coil 161 and the consequent eliminationof interference on the receiving apparatus by the transmitted frequencyf2.

On the other hand currents of frequency f1 will flow from one terminalof the coupling means thru rejector device 134, thru resistance 132,downward in the upper half of coil 158 and thence to another terminal ofthe coupling means. No current of frequency f1 will pass thru lower halfof coil 158 owing to rejector 126. The receiving apparatus willtherefore be influenced by f1. The transmitting apparatus will not owingto the fact that no current of f1 flows thru coil 157 due to rejectors126 and 135.

It will be noted that, in all the gures so far described, thediscrimination is absolute but in one direction, i. e., there is onlythe receiving apparatus which is completely shielded from thedisturbances caused by the local transmitter, the latter being protectedfrom the received waves in a relative manner only, depending on theefhciency of the rejectors and short-circuits used. These conditions maysuffice in numerous cases but it will be advisable, in many other cases,to carry out the double differentiation. This has 'been representeddiagrammatically in Figures 7, 8, 9 and 10.

Referring to Fig. 7, one terminal of the coupling means is connected tothe mid-point of winding 165 of transformer 166. The other terminal isconnected to the mid-point of winding 167 of transformers 168, as shown.

The upper extremity of winding 165 is connected to point 169 thruresistance 170, as shown. The lower extremity of winding 165 isconnected to point 169 thru reactance device 171. Reactance device 171comprises a rejector 172 to the transmitted frequency f2 and a condenser173 in series therewith for neutralizing the slight inductive reactanceoffered to the received frequency f1, rejector 172 being a substantialshort circuit to f1. Resistance balances the resistance to f1' offeredby the reactance device 171. The mid-point of coil 165 and point 169 arethereore equi-potential points for f1; but are not Tlie upper extremityof winding 167 is connected to point 17 4 thru a resistance 175. Thelower extremity of coil 167 is connected to the point 174 thru areactance device 176. Reactance device 176 comprises a rejector 177 tothe received frequency f1 and an inductive reactance coil 178 connectedin series therewith, as shown. Rejector 177 permits the easy passage off2 and inductive reactance coil 178 neutralizes the capacity reactanceoffered to f2. The resistance balances the resistance offered to f2 bythe reactance device 176.y Point 174 and the midpoint of winding 167 areequi-potential points for f2; but are not for f1. Points 169 and 174 areconnected together as shown.

Winding 179 of transformer 166 is connected to the transmittingapparatus; while winding 180 of transformer 168 is connected to thereceiving apparatus, as shown.

This system functions in the following manner. Equal currents ofreceived frequency f1, flow upward and downward thru upper and lowerhalf, respectively, of winding 165 to point 17 4. These currentstherefore, will exert no influence on winding 179 and consequently noneon the transmit` ting apparatus.

Currents of fl can not flow thru rejector 177; but they do flow downwardthru upper half of winding 167 and thence back to the coupling means.These currents influence winding 180, which in turn influence thereceiving apparatus. In a similar manner, transmitted frequency f2passes on to the coupling means; but does not aect the receivingapparatus. However it is to be understood that with this arrangementtransmission of f1 and reception of f2 may be effected.

Referring to Fig. 8, in which the same numerals indicate similar parts,one terminal of the coupling means is connected to equipotential point181 with respect to transmitted frequency f2 thru a resistance 175 andto equi-potential point 182 thru a reactance device 176, as shown.

Reactance device 176 rejects f1; but permits the easy passage of f2 andoffers substantially zero reactance to f2; resistance 175 balances theresistance of 176 to f2.

`Point 181 is connected to point 183 through another reactance device176 as shown. Point 182 s connected to point 183 through a resistance 175. The terminals of the receiving apparatus are connected across points181 and 182. These points are equi-potential points with respect to f2;but are not with respect to l.

lOint 184 is connected to point 185 through a reactance device 171 andto point 186 through a resistance 170. Point 185 .'s connected to point187 through a resistance 17() and point 186 is connected to point 187through a reactance device 171. Points 183 and 184 are connectedtogether, as shown. The transmitting apparatus is connected across point185 and 186, as shown.

Reactan'ce devices 171 and resistances 170 make equi-potential pointsout of points 185 and 186 to f1; but not to f2. Point 187 is connectedto the other terminal of the coupling means, as shown.

It is obvious that the received frequency fl does not influence thetransmitting apparat-us; nor does the transmitted frequency f2 influencethe receiving apparatus.

Referring to Fig. 9, in which the same numerals indicate similar parts,this system is somewhat similar to that of Fig. 26 with the exceptionthat two frequencles f1 and f3 may be received and one f2 transmitted.Reactance devices 195 reject f1 but act as short circuits to f2 and f3.The receiving apparatus for f1 is therefore connected acrossequi-potential points in so far as f2 and f3 are concerned. It istherefore only influenced by f1 and not by f2 and f3. Resistances 196balance the resistances offered by reactance devces to f2 and f3.

Reactance devices 197 function as short circuits to receivedfrequencies, f1 and f3, and open circuits to transmitted frequency f2.They offer zero reactance to f2. The transmitting apparatus is thereforeconnected across equi-potential points in so far as f1 and f3 areconcerned and is non-influenced thereby; but is influenced bytransmitted frequency f2.

Reactance devices 199 function as short circuits to f1 and f2 and opencircuits to f3.

They` also offer zero reactance to f3.v Resista-nces 200 balances theresistances offered to f1 and f2 b-y reactance devices 199. Thereceiving,y apparatus for f3 is therefore connected across equi-potent.al points in so far as f1 andY f2 are concerned and is non-influencedthereby g' but is influenced by f3.

Figure 10 shows an extension of the diagram of Fig. 7 to a networkcomprising the optional use of any two of the vfrequencies f1, f2, f3.The operation is obtained by associat. ng the transmission medium withany two of the terminals a., c. The circuit cells leading to the lattercould, forthat matter,

be connected in series with each other as in*` Figure 9 and it wouldthen only be `necessary to short-circuit that cell which it would not beintended to use at any given moment.

t will be possible .to connect together any number whatever of suchcells or elements, Figures 9 and 1() showing but three merely by way ofexample. vThose arrangements will be partfcularly useful in the case ofa party line'comprising several stations such as A, B, C, etc., and inwhich the various stations must be able to communicate with one another.Each station will be assigned but a.

single distinct transm'tting frequency and as,l many receivingfrequenciesr as there are other stations in the network.v Station A willtransmit, for example, on frequency f1 audits receiver will besimultaneously or alternateiy connected at f1 and f3. In that case,stationl B will always havey its transmitter branched at f2 andV willreceiveindiscriminately at f1 or f3 accordingto the station with-.whichhe desires to communicate. Liliewise, station@ will transmit at f3 andreceive at the inside terminals of the cells assigned to frequencies f1and f2 by short-circuiting or switching cut of circuit that or thosecircuit cells wahch do not correspond to the frequency transmitted byhis correspondent at that instant.

For that matter, it will be possible to combine the use of thesingle-frequency duplex method described in the preamble thereoftogether with the schematic diagram describedl with reference to Figures7 and 8, by branching al complete single frequency' duplex set acrossthe inside terminals of each circuit cell so as to permit of separatingthe dilferent duplex channels rather than the transmitted and receivedwave-lengths of a. given two-way channel.

The schematic diagrams shown in Figures 1, 2, 3, 4, 5 and 6 whichcomprise absolute selection but in one direction, may also be used forreception purposes only, particularly in the case of severalsimultaneous receptions, one of which is much stronger than the othersand which would be connected to the terminals so far allotted to thetransmitter. The weaker reception would thus be shielded from thestronger ones.

It goes without saying that the intermediate-tap transformers shown inthe various figures may be substituted by two separate transformersmounted in series or by mere impedances. It will be advisable, however,to make use of transformers or auto-transformers having reduced magneticleakage between windings and portions of windings not only with a viewof decreasing the losses b-ut mainly in order to reduce the iiiductancethereof when they operate differentially. These inductance effects mayfurthermore be com pensated by suitable capacities inserted in seriestherewith in order to bring back the current into phase with thevoltage.

It should be understood that the react-ance networks are purelyrepresentative and that they may be substitutedey their equivalents asregards operation, it being given that they always operate approximatelyeither as very large resistances (rejeotors) or very low resistances(resonant shunts).

While I have disclosed various preferred modications of my inventions, Ido not limit myself to the same; but'may employ such other modificationsas come within the spirit and scope of my inventions.

I claim:

l. In a communication system for simul-` v taneously sending messages inopposite directions, a communication channel, transmit ting apparatustransmitting on a rst given frequency and receiving apparatus receiv ingon a second given frequency connected to the same Vend of said channelas said transmitter, means whereby said receiving apparatus is connectedacross equipotential points with respect to said transmitting frequencyand said transmitting apparatus is connected across equipotential pointswith respect to the receiving frequency sent over said channel to saidreceiving' apparatus from a distant station.

2. In a signaling system for simultaneously sending messages in oppositedirections, a communication channel, transmitting apparatus andreceiving apparatus at the same end of said channel, means for placingsaid receiving apparatus at equipotential points with respect to energyfrom said transmitting apparatus, and means for placing saidtransmitting apparatus at equipotential points with respect to energyfrom the distant signal received over said channel.

LUCIEN BGIN.

